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Knee Pain

I’ve always been a sport enthusiast, although I count watching, not necessarily doing, sport in that wider category. After a brief secondary school foray into the cross country team running wasn’t really something I was either good at or enjoyed, until my 30s. When home and work life becomes increasingly hectic I think the lure of 45 minutes on one’s own outside is a great motivator. With lots of support from family and friends I have gradually increased the distance I run until I did my first marathon on my 40th birthday.

As I get older and creakier though I am starting to get niggling knee pains, classic signs of the start of mild osteoarthritis (OA). It seems natural to wonder if this could be because of my running, and would it mean that I would have to stop something that I’ve come to love. It is very logical to think that continued high impact blows to the knees would cause further damage and pain. As knee OA affects so many of us this is also a discussion played out in various different forms with lots of my patients, so I know that many of you will be interested to hear what the evidence seems to show.

Well, there is controversy – as there always is with lots of studies, done in many different ways, looking at something as complicated as the human body. However many studies fall firmly on the side of running.

There is certainly a significant body of evidence that shows running, for most people, doesn’t harm the knees, and doesn’t cause increased pain – these findings seems to be reproducible and robust. However we can interpret some studies further which seem to show that runners have LESS knee pain than non-runners. Grace Lo et al in 2017 looked at over 2000 people with a mean age of 64 and BMI of 28 (slightly overweight) so very representative of my patients presenting with knee pain. In that study runners were 24% less likely to report knee pain than those who had never run. Interestingly those that didn’t run now but had run for a while at some time in their life reported 18% less knee pain. So it seems as if the positive effects of running could well be long lasting.

So if we’re saying that running doesn’t cause knee osteoarthritis, what does? A study by Dan Lieberman et al showed that knee osteoarthritis has hugely increased in prevalence in the generations born since the Second World War. Factors responsible for this increase seem to be

1) Continuous walking on hard paved surfaces

2) High heeled shoes

3) Inactivity – a hugely significant factor for knee OA and many other diseases

Why is inactivity thought to have such an effect?

  1. I think we’d all agree that people who are more active tend to have lower body weights and therefore put less load on the knee joints, and this is certainly an important factor.
  2. Inactivity, for example sitting at a desk all day, at any age, leads to deconditioning of the body.  Joints have thinner and more fragile cartilage, and the legs have weaker stabilising muscles, leading to increased risk of injury on any movement of the joint making early onset knee osteoarthritis more likely.
  3. Exercise and activity also has an anti-inflammatory effect directly within the synovial fluid of the joint. This decreases the inflammation associated with OA of all stages. It is perhaps this ongoing reduction in inflammation, even in a ‘normal’ joint that provides the effect that running seems to have of reducing knee pain. It may also be the reason why our logical thought that high impact sports are bad is incorrect, as it is this high impact exposure that initiates the greatest anti-inflammatory effect. Exercise and activity also has a body wide anti-inflammatory effect so decreasing the risk of other inflammatory related diseases such as diabetes, cardiovascular disease, stroke and vascular dementia. It really is the drug we should all be taking.

So it seems clear that activity and exercise, to the limits of what your body can do, at any stage of knee osteoarthritis – even before you have any symptoms at all – is very useful. And if you can – run! As my grandmother repeatedly tells me at age 94 – “use it or lose it”.

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